Episodic hypersomnia, hyperphagia, and hypersexual behavior has been referred to as the classical symptom triad but is presented by only half of KLS patients. In the majority of patients, cognitive dysfunction, hallucinations, and déjà vu-like experiences accompany hypersomnia .
In detail, the following symptoms have been related to the disease :
During early stages of the disease, KLS episodes may be experienced several times a year, but frequency declines over time. Similarly, the severity of symptoms gradually decreases with disease progression. A single episode typically lasts about ten days , but may also extend over more than a month . Between episodes, affected individuals may present unaltered sleep, eating and sexual patterns, but a trend towards fatigue and higher incidence rates of anxiety and depression has been registered .
Patients may or may not be able to recall a KLS episode.
According to The International Classification of Sleep Disorders , KLS falls into the categories "hypersomnias of central origin" and "recurrent hypersomnia." Diagnostic criteria are defined as follows:
Thus, thorough anamnesis, general and neurological examinations are the mainstays of KLS diagnosis. Additional measures may be carried out to rule out psychiatric disorders.
In this context, polysomnography , brain imaging, laboratory analyses of blood or cerebrospinal fluid, and neuropsychological tests may be performed .
Kleine-Levin syndrome (KLS) is a rare disease with as-of-yet unknown etiology. Affected individuals suffer from episodic hypersomnia, cognitive impairment, and an altered mental state. It has been speculated that these symptoms indicate hypothalamic lesions, although scientific evidence regarding this hypothesis is scarce. Disease onset has been related to encephalitis , though, single episodes may be triggered by infection, head trauma, alcohol or drug abuse. Familial KLS has also been described .
To date, symptomatic treatment is not available. Spontaneous remission is likely, though, particularly in patients who experience first episodes of hypersomnia during adolescence. However, years may pass until resolution occurs .